The gene copy number (also "copy number variants" or CNVs) is the amount of copies of a particular gene in the genotype of an individual. Recent evidence shows that the gene copy number can be elevated in cancer cells. For instance, the EGFR copy number can be higher than normal in Non-small cell lung cancer. This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... The genotype is the specific genetic makeup (the specific genome) of an individual, in the form of DNA. Together with the environmental variation that influences the individual, it codes for the phenotype of that individual. ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these cells to invade other tissues, either by direct growth into adjacent tissue through invasion or by implantation into distant sites by metastasis. ... The epidermal growth factor receptor (EGFR) is the receptor for epidermal growth factor (EC 2. ... Lung cancer is a cancer of the lungs characterized by the presence of malignant tumours. ...

In certain cases, such as rapidly growing Escherichia coli cells, the gene copy number can be 4-fold greater for genes located near the origin of DNA replication, rather than at the terminus of DNA replication. Elevating the gene copy number of a particular gene can increase the expression of the protein that it encodes. Binomial name Escherichia coli T. Escherich, 1885 Low-temperature electron micrograph of a cluster of bacteria, magnified 10,000 times. ... DNA replication. ... DNA replication. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ...

Sources and notes

• Cappuzzo F, Hirsch, et al. (2005) Epidermal growth factor receptor gene and protein and gefitinib sensitivity in non-small-cell lung cancer. J Natl Cancer Inst 97: 643–655
• Atkinson M, Savageau M, Myers JT, Ninfa A (2003) Development of Genetic Circuitry Exhibiting Toggle Switch Behavior in Escherichia Coli. Cell 113: 601

Further reading

• Genome-wide analysis of DNA copy-number changes using cDNA microarrays "Gene amplifications and deletions frequently contribute to tumorigenesis. Characterization of these DNA copy-number changes is important for both the basic understanding of cancer and its diagnosis."
• New Scientist article Human DNA is far more varied than thought published November 22, 2006 "Two separate studies of the human genome have revealed an unsuspected amount of variation between people in the number of copies of genes they have. [...] They discovered that nearly 24 million nucleotides are involved in such copy number variants (CNVs). [...] They found 1447 CNVs, covering about 12% of the human genome."